Türkiye Jeoloji Bülteni

Abstract: The Oligocene sediments occuring around of Çatalca are divided in two different rockunits, i.e., sandstone-conglomerate and marl. The pre-Tertiary basement rocks are gneiss, micaschists,marble and quarzite which are representatives of the Istranca metamorphic massif.The sandstone-conglomerate unit is composed of poorly consolidated sandstone, mudstone andconglomerates as channel deposits. Local existance of coaled plant fossils and local intersupplementarycoals are observed in the sandstone section. Sedimentological and textural properties of the sandstone conglomerate unit indicate that such unit possibly deposited in alluvial environment. Lignite occurance,observed with varying dimensions which possible deposited in flood-plainmarshes of fluvial environment.The marl unit consists of mainly clayey limestone, calceraous shale, mudstone and claystone whichshow cyclic and ordered lamination. Clastic horizons which are composed of well sorted quartz-arenitsituate in many levels in marl section. Major rock components of the marl unit, indicate a lagoonal typeshallow depositionaî environment. In addition to textural properties and lateral stratigraphic variationsof quartz-arenites, represent the existance of a beach type clastic shore plains.

Abstract: In the shear zones, which are developed by ductile behaviour of crystalline rocks, the grainshape analyses were carried out and the rose diagrams of dimensional grain orientation were also produced. The geometrical variations of the shapes of the rock-forming minerals and their dimensionalpreferred orientation are related to the tectonic history of the shear zones and in agreement to theresults derived from petrofabric analyses. In spite f)i these, it can be concluded that the statistical results, obtained from the grain shape analyses, do not reflect properly the absolute amount of natural deformation and the range of strain variation within the shear belts. 

Abstract: In this study, mineralogy, petrography and geochemistry of gabbros, from Northeast ofKaman Region (Kırşehir), were investigated. Gabbros generally consist of plagioclase, hornblende, augiteand rarely olivine. Chlorite, tremolite, calcite, quartz, albite, epidote and biotite are observed as alterationminerals. The accessory minerals are magnetite, ilmenite, hematite and pyrite as opaque minerals, andalso sphene and apatite. Generally, rocks are defined as hornblende-gabbro or fine grained-gabbro. According to chemical analyses results, gabbros are crystallized from subalkaline tholeiitic type of magmaand these gabbros may represent a member of an ophiolitic sequence. 

Abstract: The genus Siderolites of the family Calcarinidae is widely observed within the Maastrichtianaged shallow-marine sedimentary sequences of Anatolia. However, as is known, the only species foundin the Maastrichtian is Siderolites calcitrapoides Lamarck. The species Siderolites denticulatus Douvillewhich is known in the Maastrichtian age sediments of Europa is determined for the first time.

Abstract: Volcanic rocks of Lower Jurassic age, which crop out in the southeast of Akhisar, haverecently been identified. They are intercalated with marine deposits, with characterize a shallowwater enviroment. Greenish compact meta-volcanics are petrographically rhyolitic. Major elementanalyses indicate that they are calc-alkaline in character.Distribution and the localitions of the Triassic and Jurassic volcanics which crop out in West Anatolia, Aegean islands and the mainland Greece are summarized on the map. Triassic volcanics aremainly spilitic and basaltic. Differentiated products are subordinate. Jurassic volcanics consist of spilitic, basaltic, andesitic and dasitic rocks.Their petrochemical character and mode of occurance are discussed in order to understand therelation between the feodynamic evolution of the region and the genesis of the volcanism during theEarly Mesozoic.On consideration of the data, the products of Triassic-Jurassic volcanism seem to be related torifting and subduction processes. 

Abstract: In this paper, the paleontologic study and the biogeography öf the species Pironaea tima.censis, P. corrugata, P. praeslavonica, P. polystyla and P. anatolica from the various localities of Tur*key, have been given.

Abstract: In the present study, the genetic interpretation of the alkaline rocks around BayındırAkpınar (Kaman) region within the Kırşehir Massif, are tried to be explained by determining their pet*rographical and geochemical properties. The alkaline rocks in the study area show a succession as syenitoids and volcanits. Syenitoids have quartz syenite and feldspathoidal syenite composition. Feldspathoidal syenites (miaskite, sodalite syenite and foyaite) are of miaskiftie character in terms of their minera*logic and chemical properties Volcanits are of phonolite and tephritic phonolite types.Basing on their petrographical and geochemical properties, the rock associations in concern are formed from different magmas derived from different source meterials, but not from the fractional crystallization of a single magma. 

Abstract: The «Permo carboniferrious of Demirözü» crops out north of Demirözü, about 35 kilometers west of Bayburt (Gümüşhane The .succession, Upper Gartroniferous-Lower Permian in age, is prominent for its coal lenses. The;"areap,"where this unit is exposed, is Characterised by E-W trending nu*merous thrust sheets dipping söûtn & The Carboniferous and the Permian are well exposed in two thrustsheets located south of «Bayîburt-Plain», fhe Carboniferous consists of. conglomerate, sandstone, orthoquartzite, carbonaceous shale and limestone arid ite base is not exposed in the northern slice. It is ona rnetomorphic basement. and grades iritö Permian consisting of conglomerate, sandstone, quartzite,siltstone and limestone. The Palaeozic is covered by the.overlapping Liassic consisting of conglomerate, sandtone, sandy &mestone and dolomitic limestone. J)pgger and Malm are represented by micrite with local chert intercalations. These grade in Lower Cretaceous units consisting of intercalated sandstones and calcarenitesthat are tectonically overlain by a` völcanö-şedinıentary sequence of Liassic-Upper Jurassic (?) age. Inthe third slice, the volcano-sedimentary" secjuence is unconformably underlain by metamorphic rocks.This volcano-sedimentary sequeabo  at the base, of conglomerates and plant bearing sandsto*nes. It grades in Upper .Jurassic cower Cretaceous limestones in the uppermost section.The metamorphic rocks and 4he overlying Per mo-Carboniferous are allochthonous in the investigated area. The thrust sheets comprising" slices of Upper Cretaceous sediments and ophiolites are presetved in front of north moving thrust sheets that are mutually covered by Eocene, suggesting the move*ments to. have occurred in the Upper* Çfeiade.ous-Eocene interval.

Abstract: Meandering and braided stream deposits of the Paleocene, which are widespreaded towardsthe west, are exposed in northern Ankara region particularly a tthe vicinities of Lezgi, Orhaniye andKınık villages. The braided stream deposits, approximately 250m, which occur at the bottom of Paleocene continental units, are made of many individual channel-fills and gravelly channel bars superimposedeach other. Lithofacies analyses dependyon Miall (1977)`s definitions showed that the braided streamsediments had been accumulated under tectonic control as both transition and allocyclic sequences,From the base to top, the allocyclicity order is; Donjek type sequences -* Platte type sequences —»Donjek type and Scott type sequences. That cyclicity represents that intensive epirogenic/tectonic movements effected in Ankara region during the Plaleocene time.

Abstract: The alternating deposition of resedimented muds tone, bioclastic packgrainstone and fi*nely grain quarz sandstone have been formed as cyclic sediments during storm stages in the Carboniferous succession of Naltaş area. High energy conditions effective during the storm gave rise to laterallmovement of the carbonate sediments and erosion of sea bottom from opening shore to nearshor. Innerstructure of the storm deposite, «Tenıpestite» that may be misinterpreted as türbidite beds, shows fi*ning upward sequence, of which lower and middle part have been characterized by coarse grain skele^tal pack-wackestone with essentially paralel oriantation of the biogenic contituents, whereas the upperpart composed of paralel or cross-laminated silt-mud stone. The last produce, mudstone include rich orga*nic material would be originated from plant, possible source sea grass eroded from sea floor. The stormdeposites were covered with thick carbonate mud as autochtonous sedimentation during post-stormperiods.